Spurred by new resources on the Internet, the ranks of amateur genealogists are growing, and millions of family trees are flourishing

"Please, will somebody help me? I'm new at this, and I have no idea what I'm doing."

Those words were not some perverse message smeared in lipstick across a rest-room mirror. They were posted on the volunteers' bulletin board of America Online's genealogy site, typed by G. Marie Leaner, a communications consultant in Chicago, looking for her family roots.

Leaner's plaintive cry was heard by a volunteer researcher, who told Leaner about the Social Security Death Index. That was the breakthrough Leaner needed, allowing her to move out onto the Internet and into libraries, gathering snippets about her heritage. Now, thanks...